Plunger pump



N. B. TVEDEN Sept. 29, 1953 PLUNGER PUMP 2 Sheets-Sheet 1 Filed July 11,1947 6 an I N T I m w 1 I a F I U 8 u o a a. u 0 1 m 3 m 2 PL- 1| 2! v M6 9 a 1 v 4" 6 2 M w a WP J T 0 \Q: 3 A I u :4 u {I I I.

Clttomeg Patented Sept. 29, 1953 PLUNGER PUMP Niels Brge Tveden,Copenhagen, Denmark, assignor to Dacola Maskinfabrik A/S, Copenhagen,Denmark, a. corporation of Denmark Application July 11, 1947, Serial No.760,392 In Denmark July 27, 1946 4 Claims. 1

This invention relates to high-speed, single or multi-cylinder plungerpumps of the kind in which the crank imparts to each cylinder anoscillating movement which is utilized for compulsory control of theadmission and discharge of the working medium by co-operation betweenorifices in a lateral surface of the cylinder and in a countersurface,against which the first-mentioned surface is held in abutment.

The main object of the invention is to provide a pump of this kind,capable of producing a comparatively high pressure, and which can beoperated at very high speeds. Another object of the invention is toadapt the pump in such a manner that the higher the pressure produced bythe pump, the greater the tightness of the valve gear. A further objectof the invention is to adapt the pump in such a manner as to avoid thatthe working medium in the latter pump design flows through that part ofthe pump casing in which the shaft of the pump and the crank or cranksare located. Finally, the invention has for its object to provide a pumpof the kind in question which is simple in construction, easilyassembled and disassembled and moreover very reliable in operation.Still further objects of the invention will be disclosed by thefollowing description with reference to the drawings, in which Figure 1is a vertical axial section of an embodiment for a twin-cylindertwo-stage pump for use as a compressor in a refrigerating plant.

Figure 2 is an end view of same, the cover of the pump casing beingremoved, certain parts being shown in section on the line II--II inFigure 1.

Figure 3 is a partial section on the line III--III of Figure 1.

Figure 4 is another embodiment with a single cylinder, in vertical axialsection.

Figure 5 is an end view of same, the cover of the casing being removedand certain parts shown in section on the line V--V in Figure 4.

Figure 6 is the top part of the casing for this pump as seen from theinterior, with the cover removed.

Figure 7 is a third embodiment, likewise with a single cylinder, invertical axial section.

Figure 8 is a section on the line VIII-VIII in Figure 7 Figure 9 is thetop part of the casing of this pump as seen from the interior, with thecover removed.

Figure 10 is a fourth embodiment with two cylinders, for use as atwo-stage compressor, in vertical axial section.

Figure 11 is a section on the line XI-XI in Figure 10.

The pump shown in Figures 1-3 consists of a casing [0, one end of whichis closed by a cover l2 secured by means of screws I3. The opposite endof the casing is provided with a bored neck I4 forming a bearing for acrankshaft 16 with an enlargement l8 constituting the journal of theshaft H5 in the bearing and accommodating a stuffing box, of which nofurther description is given, sinceit is outside the scope of theinvention. The shaft I6 is passed through the neck 14 and may outsidethe latter be coupled directly to a driving motor. The shaft is providedwith two cranks 22 and 24 and a gudgeon 26 co-axial with the enlargementl8 and resting in a stud 28 on the inner side of the cover I2.

The pump has two cylinders, worked out dia metrically in substantiallydisc-shaped bodies 30 and 32 which are placed in a bore 33 at the top ofthe casing to parallel to the crankshaft It. The said bore 33 ismoreover provided with a machined plane surface 34 forming a support forone lateral surface of the body 30. The body 32 is supported against theopposite side of the body 30, and in the bore 33 on the other side ofthe body 32 is inserted a disc 36 which is secured against turning andheld in abutment against the said body by means of a coil spring 38. Thecylinder bores of the bodies 30 and 32 accommodate plungers 40 and 42,respectively, having two-piece bearings 44 and 46 co-operating with thecranks 22 and 24, respectively. The plunger 40, which acts as a lowpressure piston, is of a larger crosssectional area than the plunger 42,which acts as a high pressure piston, and the cranks 22 and 24 areoffset by in relation to each other, the two plungers thus working inpush-pull.

The face 34 of the casing l9 against which the body 30 abuts, isprovided with an opening 43, see Figure 3, which forms the inlet openingof the pump. The top end of the cylinder in the body 30 is provided witha cross-passage 50 constituting both the inlet and the discharge channelfor this cylinder. Similarly, the body 32 has a passage 52 constitutingthe inlet and discharge channel of the cylinder in that body. Finally,an opening 54 in the disc 36 constitutes the discharge opening of thepump.

In the opening 48 is screwed a pipe branch 56, to which the supply pipeof the pump can be connected, and in the cover I2 is inserted a nipple58 for connection to the discharge pipe. A cupshaped diaphragm 60,which, for example, may be of copper, is soldered along its edge to thedisc 36, whereas the nipple 58 is passed through 3 the diaphragm bottom,keeping the diaphragm in position between a collar on the nipple and thecover I2.

When the compressor is turned clockwise from the position shown inFigure 2, the upper part of the body 30 will by its oscillation be movedupwards as in Figure 3, and the upper part of the body 32 will be moveddownwards. After a slight movement the cylinder of the body 30 willregister with the inlet opening 48, and the cylinder in the body 32similarly register with the dis.- charge opening 54. The working mediumwillbe drawn into the first-mentioned cylinder, and the pre-compressedmedium in the last-mentioned cylinder will be forced out. During theseoperations there will be no inter-communication between the twocylinders. When the crank 22 has passed its lower dead centre and thecrank 24 has passed its upper dead centre, inter-communication will beestablished between the passa es 50 and 52 owin to h o l tin m v ment ofthe cylinders, whereas the said passages will be cut off from theopenings 48 and 54, respectively. Thus, the charge in the cylinder ofthe body 30 will be transferred to the cylinder of the body 32 whichinvolves a pie-compression of the medium, since the first-mentionedcylinder is bi ger than the last-mentioned one.

The medium leaving the compressor will flow to the space formed betweenthe disc 36 and the diaphragm 60 and consequently exert a pressure aainst the said disc, which, again, because of the diaphragm beingslightly resilient, will exert a pressure on the body 32, forcing itagainst the body 30 and further pressing the latter against the surface34 of the casing I0. The pressure between the abutting surfaces of thesaid parts will therefore be substantially proportional to the pressureproduced by the pump on the working medium, which is very purportablewith a view to maintaining constant tightness between the co-operatingsliding surfaces of the said parts. The spring 38 may be comparativelylight or may, for example, be dispensed with altogether, the diaphragm60 being capable of exerting the slight pressure necessary on the disc36 until a pressure on the working medium has been established.

As plainly indicated in Figure l, the bodies 30 and 32 are onlycontacting the corresponding counter surfaces at the edge of theirlateral surfaces. This will ensure an even wear of the sliding surfaces,so that the tightness between same at the inlet and outlet openings,which are eompulsorily controlled by means of the oscillating movementof the bodies 30 and 32, is maintained even after operation over a longperiod. The said bodies may be provided with recesses 62, as in Figure2, in order to reduce weight.

Owing to the bodies 30 and 32 being placed in direct contact with eachother, the dead space existing between the stages of the compressor maybe materially reduced.

Referring to Figures 4-6, the reference numbers I0, I2 I3, I4, etc, and22 denote the same parts as the corresponding reference numbers inFigures 1-3. The pump shown here has a single cylinder provideddiametrically in a substantialiy disc-shaped body I24 which, as in theformer case, is Journalled in a bore I26. The body I24 rests with one ofits lateral surfaces against a machined surface I28. At the oppositelateral surface of the said body is provided an annular projection I30enclosed by a coil spring I32 4 forcing the body I24 against the surfaceI28. The cylinder bore of the said body accommodates a plunger I34 witha bearing I36 cooperating with the crank 22.

The surface I28 is provided with an opening I38, see Figure 6,constituting the inlet opening of the pump. The discharge openingconsists in the case of this embodiment of a recess I40 surrounded bythe surface I28, as will appear from the following. At the top thecylinder body I24 has an opening I42 forming the inlet and outletpassage for the cylinder.

The supply pipe of the pump can be connected to a pipe branch I44screwed into the opening I38. In the cover I2 there is inserted a nippleI46 for connection to the discharge pipe, the said nipple being co-axialwith the axis of oscillation of the cylinder body I24. The opening ofthis nipple is closed inwardly by means of a. ball I48 forming a supportfor a cone disc I50, the edge of which serves as a support for thespring I32, At its inner end the nipple I46 is provided with threeradial bores I52 opening downwards and laterally, whereas there is nocorresponding bore facing upwards. The said bores form communicationbetween the space of the casing I0 and the nipple I46, moreover, thereis a slot I 41 between the edge of the disc I50 and the interim sidesurface of the cover I2.

When the shaft I6 is turned, the cylinder body I24 will perform anoscillating movement. With the plunger I34 in its top position asindicated in Figure 4, the opening I42 will be covered by that part I54of the surface I28 which is immediately to the right of the opening I38,see Figure 6. When the shaft I6 is turned in the direction of the arrowshown in Figure 5, the opening I 42 will register with the opening I38during the downward stroke of the plunger. This communication will againbe cut off at the lower dead centre of the crank 22, and during thefurther movement the opening I42 will get into communication with therecess I40. In operation of the pump a suction from the branch pipe I44will thus alternate with an exhaust to the recess I40. From thelastmentioned recess the working medium can flow through passages I50 inthe body I24 to the space of the casing I0 proper, from which it mayescape through the slot I41, previously referred to, at the edge of thedisc I50, and through the bores I52 to the discharge nipple When thepump is in operation, the pressure on the working medium will be presentin the casing I0, and as the cylinder body I24 has a larger free area onits left side, see Figure 4, than on its right side, this pressure willcontribute towards maintaining abutment between the cylinder body andthe surface I28. The spring I32 need only exert a comparatively lightpressure against the body I24, as its object only is to produce thenecessary contact pressure in case of insufficient pressure on theworking medium.

The lubrication oil is fed to the bottom of the casing I0, being thrownabout by the movement of the crank 22 and supplied to all surfacesrequiring lubrication, an annular passage I58 being provided so as alsoto secure lubrication oi the circumferential surface of the body I24.The space in the pump casing serves as an oil separator, because therate of flow of the working medium through this space is very slow. Thedisc I50 protects the nipple I46 from oil splashes.

The embodiment shown in Figures 7-9 is mainly distinguished from thatreferred .to in Figures 46 thereby that the working medium does not passthe entire space of the pump casing, but only part of it, serving as anoil separator, the working medium thus being not admitted to that partof the pump casing accommodating the crank.

Referring to Figures 7-9, the cylinder body is denoted by 224. In thepassages 256 of the said body there are partitions 251, so that therecess 240 in the pump casing will have an opposite recess 24! in thecylinder body 224. The inlet opening 238 of the pump is located as inthe former case, whereas the discharge opening 243 is located in theside wall of the pump casing at the recess 240. The exhaust from thepump on leaving the space 240, 24! will therefore pass directly to thedischarge opening 243. A further description of the construction of thisembodiment seems superfluous.

When the compressor is put into operation, the pressure established onthe working medium will initially be present in the space 240, I. Thespring 232 acting on the cylinder body 224 is, however, so powerful thatthe abutment pressure between the said body and the opposite surface 228will not be relieved. The pressure in the said space will gradually bediffused to the entire space of the pump casing, and in case ofequivalent pressures in both spaces, the pressure of the working mediumwill, as in the former case, contribute towards keeping the cylinderbody in abutment. This effect, however, is not required in theembodiment described, the spring 232 alone being capable of providingthe necessary abutment pressure.

It is immaterial that the opening 238 serves as inlet and the opening243 as discharge, it being also possible to design the machine in such away that the working medium flows in the opposite direction.

The two-stage compressor shown in Figures 10 and 11 has two cylinderbodies 348 and 35!) actuated by separate cranks 352 and 354 on the crankshaft 356. The pump casing 358 is provided with two covers 360 and 362,both with bearings for the crankshaft 356 and each constituting anendwall of the casing, and one of which has a neck 364 for a stufllngbox.

Each of the cylinder bodies 348 and 350 abuts against its own cover 366and 362, and the spaces thus formed, 366 and 368 respectively, areinterconnected through passages 31!) in the cylinder bodies, see Figure11. The cylinder bodies are disposed at a certain distance from eachother in axial direction, and between the said bodies there is provideda space 314, limited by an annular element 312, through which space thesaid communication passes, being separated from that part of the pumpcasing accommodating the cranks 352 and 354. Between the cylinder bodiesis provided a spring 316 forcing the said bodies away from each othertowards their respective counter surfaces.

When the pump is in operation, the working medium is drawn in through anopening 318 in the cover 360 and conveyed to the space 366 by thereciprocating movement of the plunger in the cylinder body 348. Thespaces 366 and 368 and the passages 310 in the cylinder bodies, whichlatter passages provide communication between the said spaces, form,together with the space 314 in the element 312, a receiver for admissionof the pre-compressed working medium. The secondary compression iseffected by means 6 of the plunger working in the cylinder body 350, thesaid plunger taking off the pre-compressed medium from the receiver andforcing it to the outlet opening 380 of the pump provided in the cover362.

A further description of the mode of operation of this pump isconsidered unnecessary in view of the detailed description given of theembodiments previously mentioned.

The invention is more particularly intended for use in compressors ofsmall refrigerating plants, for example, for household purposes. In suchplants the compressor has hitherto been driven through a speed reducer,the springloaded valves used for ordinary compressors not being capableof working at the speed corresponding to that of the motor in the caseof direct coupling with the motor. A compressor according to the presentinvention, however, can be coupled directly to a high-speed motor,because the inlet and the outlet openings of the compressor are subjectto compulsory control.

If it is preferred not to use any stuffing box in the compressor at all,the compressor casing may be designed so as to enclose the driving motortoo, for example an electromotor, thus practically eliminating anypossibility of leakage.

Having thus fully described my invention I claim as new and desire tosecure by Letters Patent:

1. A plunger pump having at least two cylinders, of the type in which anoscillatory movement is imparted to the cylinders, consisting of a pumpcasing having a bore, two disc shaped cylinder bodies, each with acircumferential surface of rotation surrounding the correspondingcylinder and journalled oscillatory in said bore, each of the saidcylinder bodies having one end surface in abutment against a surface atthe inner side of the pump casing at one of the ends of said bore, eachof said last named surfaces being provided with a recess which togetherwith the correspondin cylinder body forms a space, said spaces beinginterconnected by pas sages in the cylinder bodies and forming togetherwith said passages a part of a receiver, arranged inside the pumpcasing, for the working medium of the pump.

2. A plunger pump as claimed in claim 1, in which the two cylinderbodies are disposed at a distance from each other in the direction oftheir axes, an annular element restricting the space between the twobodies and constituting another part of the receiver, a spring beingmounted in said annular element to force the bodies away from each otheragainst the surfaces at the inner side of the pump casing.

3. A plunger pump, comprising a pump casing having a bore, and inlet andoutlet openings and at least one cylinder body having a cylinder thereinand a surface of rotation surrounding said cylinder, said body beingjournalled oscillatory in said bore in said pump casing, a planesubstantially annular counter surface inside said pump casing, said bodyabutting with a lateral surface against said plane substantially annularcounter surface inside the pump casing, said lateral surface beingprovided with a passag leading to the cylinder, said counter surfacebeing provided with an orifice connected to one of said openings in thepump casing, a recess, facing towards the cylinder body, in the pumpcasing and being encircled by the counter surface, oscillatory movementof the cylinder body alternately connecting said passage to said oriitswayfrom .the inlet to the outlet in the pump casing.

4. A plunger pump as claimed in claim 3, in 5 which communication isestablished between said recess and the space of the pump casing at theother sideof said cylinder body,.said inlet and outlet openings in -thepump casing being arranged on opposite sides of the cylinder body. 10

NIEIS BQRGE 'I'VEDEN.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date Case Nov. 18, 1890 Atkins May 16, 1922 Harr et al. Feb. 5,1929 I-Ivid Feb. 26, 1929 Carrey Dec. 29, 1931 Fourness Apr. 25, 1933Smith Jan. 23, 1934 Smith Oct. 23, 1934

